Investigation and assessment of the edge grip of snowboards with laser vibrometry - A proposal of a standardised method

The edge grip of a snowboard defines its ability of holding the arc of a carving turn without intending to break out. In order to assess the vibrational movements of the edge under simulated loading conditions, two boards were put on the edge on a soft foam surface and loaded with 400 N such that the boards bent under the added load and the edge was in full contact with the surface. The shovels of the boards were excited with a swept sine signal from 5-200 Hz and the displacements measured with a laser vibrometer. The last edge point in contact with the surface proved to have the largest movement range. Maximal displacement was caused by the first torsional mode at 115-125 Hz, followed by combined bending/torsional modes at lower frequencies (23-30Hz, 80-90 Hz). One board exhibited a larger movement range in the first torsional mode compared to the other board, and the frequency peak of this mode was wider. The mobility index of this board, introduced in this study as the normalized area under the displacement curve of the last edge point, was 1.5 times higher than the index of the other board. The method used in this study offers an accurate quantification of the movement of the edge under standardized load conditions.